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197 lines
6.4 KiB
197 lines
6.4 KiB
git-blame(1) |
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============ |
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NAME |
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---- |
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git-blame - Show what revision and author last modified each line of a file |
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SYNOPSIS |
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-------- |
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[verse] |
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'git blame' [-c] [-b] [-l] [--root] [-t] [-f] [-n] [-s] [-p] [-w] [--incremental] [-L n,m] |
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[-S <revs-file>] [-M] [-C] [-C] [--since=<date>] |
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[<rev> | --contents <file>] [--] <file> |
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DESCRIPTION |
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----------- |
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Annotates each line in the given file with information from the revision which |
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last modified the line. Optionally, start annotating from the given revision. |
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Also it can limit the range of lines annotated. |
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This report doesn't tell you anything about lines which have been deleted or |
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replaced; you need to use a tool such as 'git-diff' or the "pickaxe" |
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interface briefly mentioned in the following paragraph. |
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Apart from supporting file annotation, git also supports searching the |
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development history for when a code snippet occurred in a change. This makes it |
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possible to track when a code snippet was added to a file, moved or copied |
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between files, and eventually deleted or replaced. It works by searching for |
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a text string in the diff. A small example: |
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----------------------------------------------------------------------------- |
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$ git log --pretty=oneline -S'blame_usage' |
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5040f17eba15504bad66b14a645bddd9b015ebb7 blame -S <ancestry-file> |
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ea4c7f9bf69e781dd0cd88d2bccb2bf5cc15c9a7 git-blame: Make the output |
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----------------------------------------------------------------------------- |
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OPTIONS |
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------- |
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include::blame-options.txt[] |
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-c:: |
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Use the same output mode as linkgit:git-annotate[1] (Default: off). |
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--score-debug:: |
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Include debugging information related to the movement of |
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lines between files (see `-C`) and lines moved within a |
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file (see `-M`). The first number listed is the score. |
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This is the number of alphanumeric characters detected |
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to be moved between or within files. This must be above |
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a certain threshold for 'git-blame' to consider those lines |
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of code to have been moved. |
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-f:: |
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--show-name:: |
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Show filename in the original commit. By default |
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filename is shown if there is any line that came from a |
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file with different name, due to rename detection. |
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-n:: |
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--show-number:: |
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Show line number in the original commit (Default: off). |
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-s:: |
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Suppress author name and timestamp from the output. |
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-w:: |
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Ignore whitespace when comparing parent's version and |
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child's to find where the lines came from. |
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THE PORCELAIN FORMAT |
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-------------------- |
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In this format, each line is output after a header; the |
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header at the minimum has the first line which has: |
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- 40-byte SHA-1 of the commit the line is attributed to; |
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- the line number of the line in the original file; |
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- the line number of the line in the final file; |
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- on a line that starts a group of line from a different |
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commit than the previous one, the number of lines in this |
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group. On subsequent lines this field is absent. |
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This header line is followed by the following information |
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at least once for each commit: |
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- author name ("author"), email ("author-mail"), time |
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("author-time"), and timezone ("author-tz"); similarly |
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for committer. |
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- filename in the commit the line is attributed to. |
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- the first line of the commit log message ("summary"). |
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The contents of the actual line is output after the above |
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header, prefixed by a TAB. This is to allow adding more |
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header elements later. |
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SPECIFYING RANGES |
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----------------- |
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Unlike 'git-blame' and 'git-annotate' in older git, the extent |
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of annotation can be limited to both line ranges and revision |
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ranges. When you are interested in finding the origin for |
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ll. 40-60 for file `foo`, you can use `-L` option like these |
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(they mean the same thing -- both ask for 21 lines starting at |
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line 40): |
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git blame -L 40,60 foo |
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git blame -L 40,+21 foo |
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Also you can use regular expression to specify the line range. |
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git blame -L '/^sub hello {/,/^}$/' foo |
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would limit the annotation to the body of `hello` subroutine. |
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When you are not interested in changes older than the version |
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v2.6.18, or changes older than 3 weeks, you can use revision |
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range specifiers similar to 'git-rev-list': |
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git blame v2.6.18.. -- foo |
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git blame --since=3.weeks -- foo |
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When revision range specifiers are used to limit the annotation, |
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lines that have not changed since the range boundary (either the |
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commit v2.6.18 or the most recent commit that is more than 3 |
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weeks old in the above example) are blamed for that range |
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boundary commit. |
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A particularly useful way is to see if an added file have lines |
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created by copy-and-paste from existing files. Sometimes this |
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indicates that the developer was being sloppy and did not |
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refactor the code properly. You can first find the commit that |
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introduced the file with: |
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git log --diff-filter=A --pretty=short -- foo |
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and then annotate the change between the commit and its |
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parents, using `commit{caret}!` notation: |
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git blame -C -C -f $commit^! -- foo |
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INCREMENTAL OUTPUT |
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------------------ |
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When called with `--incremental` option, the command outputs the |
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result as it is built. The output generally will talk about |
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lines touched by more recent commits first (i.e. the lines will |
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be annotated out of order) and is meant to be used by |
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interactive viewers. |
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The output format is similar to the Porcelain format, but it |
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does not contain the actual lines from the file that is being |
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annotated. |
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. Each blame entry always starts with a line of: |
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<40-byte hex sha1> <sourceline> <resultline> <num_lines> |
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+ |
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Line numbers count from 1. |
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. The first time that commit shows up in the stream, it has various |
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other information about it printed out with a one-word tag at the |
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beginning of each line about that "extended commit info" (author, |
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email, committer, dates, summary etc). |
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. Unlike Porcelain format, the filename information is always |
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given and terminates the entry: |
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"filename" <whitespace-quoted-filename-goes-here> |
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+ |
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and thus it's really quite easy to parse for some line- and word-oriented |
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parser (which should be quite natural for most scripting languages). |
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+ |
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[NOTE] |
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For people who do parsing: to make it more robust, just ignore any |
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lines in between the first and last one ("<sha1>" and "filename" lines) |
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where you don't recognize the tag-words (or care about that particular |
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one) at the beginning of the "extended information" lines. That way, if |
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there is ever added information (like the commit encoding or extended |
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commit commentary), a blame viewer won't ever care. |
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SEE ALSO |
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-------- |
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linkgit:git-annotate[1] |
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AUTHOR |
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------ |
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Written by Junio C Hamano <junkio@cox.net> |
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GIT |
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--- |
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Part of the linkgit:git[1] suite
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